1. Field of the Invention
The present invention relates to electrostatic chucks formed in processing chambers of semiconductor processing apparatuses, and relates to production methods therefor. In particular, the present invention relates to an electrostatic chuck which can be repeatedly used under high temperature conditions during semiconductor production and in which a feeder terminal portion can be reused, and relates to a production method therefor.
2. Description of the Related Art
Electrostatic chucks are provided in processing chambers for semiconductor production. Wafers are attracted to be fixed to the electrostatic chuck, and semiconductors are formed thereon. As shown in FIG. 1, the electrostatic chuck is provided with a substrate 1, a dielectric layer 2, and a feeder terminal portion 3. Medium channels 1a are appropriately formed in the substrate 1. The upper face of the substrate 1 is covered with the dielectric layer 2. An internal electrode 2a is embedded in the dielectric layer 2. The feeder terminal portion 3 extends from the lower side of the substrate 1 to the internal electrode 2a. An electrode 3a is embedded in the feeder terminal portion 3. In the feeder terminal portion 3, various structures thereof have been proposed in recent years since the feeder terminal portion 3 is an important member of the electrostatic chuck, on which bias voltage is applied by an external device.
In conventional techniques relating to devices having a feeder terminal, for example, a feeder terminal connection structure of a ceramic heater is disclosed in Japanese Unexamined Patent Application Publication No. 2002-203660 and Japanese Unexamined Patent Application Publication No. 2002-203661 as described below. That is, the ceramic heater has a ceramic substrate having a heating face and a heating element on the face opposite to the heating face thereof. The feeder terminal connection structure of the ceramic heater has a feeder terminal which is clipped at the edge portion of the heating element and is electrically connected thereto. In a case in which the above technique relating to the feeder terminal is applied to an electrostatic chuck as shown in FIG. 2, a feeder terminal portion 11 is structured such that an electrode 11a is covered with a sprayed coating 11b and a resin layer 11c, and the sprayed coating 11b is covered with a resin layer 11d. An electrostatic chuck is obtained such that the above feeder terminal portion 11 is integrated with a metal substrate 12a and a dielectric layer 13 having an internal electrode 13a therein. In the chamber used during semiconductor production, the lower side of the feeder terminal portion 11 is under the air, and the upper portion of the dielectric layer 13 is under a vacuum. Therefore, good gas-tightness is required to fix the above members of the feeder terminal portion 11 to each other and to fix the above members thereof and the substrate 12 to each other. Due to this, adhesives are used to fix the electrode 11a, sprayed coating 11b, and resin layers 11c and 11d to each other, and are used in fixing these members 11a, 11b, 11c and 11d and the substrate 12 to each other.
However, in the electrostatic chuck as shown in FIG. 2, the above members 11a, 11b, 11c, 11d and 12 were fixed to each other via the adhesives, and the temperature in the chamber during semiconductor production was more than 200° C. Due to this, the above members 11a, 11b, 11c, 11d and 12 were insecurely fixed to each other, and the gas-tightness thereamong was degraded. In addition, in some cases, vacuum leak occurred via the electrostatic chuck in the chamber. Due to this, electrical discharge may occur between the electrode 11a and the substrate 12 and dielectric breakdown may occur therebetween. When the dielectric breakdown occurs therebetween, the feeder terminal portion must be replaced with a new one. However, it is difficult to replace the feeder terminal portion with a new one in the above case in which the feeder terminal portion is fixed to the substrate via adhesives. The dielectric layer may be destroyed when the feeder terminal portion is replaced with a new one.
The insulation property of the dielectric layer 13 of the electrostatic chuck is degraded when the chamber is repeatedly used for semiconductor production. Due to this, it is necessary to replace the dielectric layer 13 with a new dielectric layer 13. A method for replacing the dielectric layer 13 with a new dielectric layer 13 is used such that the dielectric layer 13 having internal electrode 13a is removed and a new dielectric layer 13 is formed by thermal spraying. However, when the dielectric layer 13 is completely removed, the upper portion of the feeder terminal portion 11 projects upward with respect to the substrate 12, and it is possible that it may thereby be cut. In this case, it is necessary to replace not only the dielectric layer 13 but also the feeder terminal portion 11 with new ones, and this would be contrary to the goal of conserving resources. When the dielectric layer 13 is cut in the state in which the feeder terminal portion 13 is fixed in the substrate 12, the feeder terminal portion 13 is damaged. In addition, it is difficult to respray on the substrate 12 since the processing therefor is time consuming. When respraying is possible, the number of times it can be done is limited.
Therefore, in recent years, technique improvements in electrostatic chucks are required as follows. That is, the electrostatic chuck can be repeatedly used under temperatures of more than 200° C. during semiconductor processing. It is unnecessary to replace the feeder terminal portion of the electrostatic chuck with a new one when the dielectric layer is replaced with a new one. In other words, the feeder terminal portion can be reused or can be mounted so as to be replaceable.